Flasher relay



y 1942- H. E. ASHWORTH 2,282,446

FLASHER RELAY Filed Jan. 24, 1941 Patented May 12, 1942 FLASHER RELAY Harry E. Ashworth, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application January 24, 1941, Serial No. 375,753

6 Claims. (Cl. 172-126) My invention relates to flasher relays and more particularly to relays of this type operating on direct current and having a relatively slow rate of operation or flashing. My invention is particularly Well adapted for use on airplanes for flashing the tail lamps thereof but is not limited to such use and is useful wherever a reliably operating flasher of small size and low power consumption is required.

One object of my invention is to provide a flasher relay which has a substantially constant flashing rate notwithstanding relatively wide fluctuations in the applied voltage. Anotherobject of my invention is to provide a flasher relay which is substantially unaffected by changes in position or orientation, as when mounted on aircraft, or by ordinary vibration encountered in such service. Other objects and advantages will become apparent from the description which 101- lows.

I accomplish the foregoing objects by provid-' ing a delay mechanism controlled by a retarding magnetic field so arranged as to exert a greater or smaller retarding force in accordance with the applied voltage, thus compensating for variations in this voltage. I also design and arrange the movable parts of the flasher in such a manner, and counterweight certain members for service on moving air craft where space and weight factors and wide changes in temperature, operating voltage, and position with respect to the horizon impose unusual and difficult restrictions. A satisfactory airplane flasher relay must not only be small, compact, and lightweight, but must operate reliably under the stringent conditions of flight service. Moreover, the relay must be susceptible of quantity production and duplication at relatively low cost. The flasher relay embodying my invention is believed to satisfy all of the above requirements in a practical manner, as will appear from the description which follows.

Referring to Figs. 1 and 2 of the drawing, the relay frame 2 is made of two magnetizable portions or side pieces 2a and 2b which are joined together by the magnetizable yoke 3 to provide themain magnetic circuit which includes the main pole pieces 4a and 4b. The yoke 3 supports the operating coil 5 which, when energized, causes the-armature 6 which is pivoted at I to be attracted to the pole pieces la-4b. The armature 6 has an elongated portion or extension 8 which drives a rack 9 supported at Ill in the stirrup formed at the end of the armature extension. The rack 9 engages a pinion H and is kept in constant engagement therewith by means of the spring I2. The pinion II is carried by a shaft 13 which also carries the retarding vane I4 made of aluminum or other conducting but non-magnetizable material. The vane I4 moves in the auxiliary or retarding field which is effective in the air gap established by the retarding poles l5a-l5b. If it is desired to increase the retardation on the vane still further, a permanent magnet 18 may be used for this purpose. The retarding field is, of course, established along with the operating field which attracts armature 6, when'the operating coil 5 is energized.

The mechanical torque of the armature 6 and rack '9 is substantially balanced by a suitable counterweightv I! so as to permit operation of the relay in any position, the release torque being provided by the spring H3. The frame member 2a also carries a contact assembly comprising a contact finger 20 which closes a back contact 2i!--2| at one extreme end of the vane stroke when the relay is deenergized, and which may be used to close a front contact 2B22 at the other end of the vane stroke. The contact finger 20 is of the toggle type and is retained in its last operated position by means of a spring 23. Since the details of construction of this contact form no part of my invention and its operation is obvious, this portion of the relay will be clear without further description. It will be sufficient to point out that as the vane l4 approaches its deenergized position, the contact-operating pin 24 engages the under side of finger 2t and causes the finger to snap over to the upper position in which the back contact 2ll2| is closed. As the armature 6 approaches itsfully energized position. the pin 25 (now moving in a counterclockwise direction) engages the upper side of finger 20 and snaps the back contact 20-2l open, closing front contact 20-22 so that a control circuit can be closed through the latter contact, if desired.

The flasher relay may be provided with a switch S which, when closed, causes current to be supplied to the coil 5 for energizing the fiasher relay. Connected across the coil is a suitable indicating device L which, in airplane service, would be the usual tail lamp. As soon as energy is applied to the relay coil, the armature 6 exerts an upward force which is transmitted through the rack and pinion to the vane I4 whereupon the vane begins to rotate in the counterclockwise direction. If the applied voltage is high, the armature force is also high so that the vane tends to rotate with increased speed. However, the increased voltage also causes an increase in the strength of the retarding field developed by poles |5a,-l5b, so that the vane speed is prevented from increasing appreciably. If the applied voltage decreases, tending to cause the vane speed to decrease, the retarding field strength also decreases. It appears clear, therefore, that the vane speed tends to remain substantially constant irrespective of variations in the applied voltage.

If desired, the retarding magnetic field can be separate from the operating magnetic field and be energized from a second winding which is connected in parallel or in series with winding 5 and which magnetizes the poles l5a--l5b. Since an increase or a decrease in the operating voltage will affect both magnetic fields, compensation for voltage variation is provided by this modified form of the apparatus.

Assuming again that energy has been applied to the coil 5 by closing the switch S, the vane I4 will continue to rotate until the pin 25 engages the top side of contact finger 20 and snaps contact 20-2! open. The opening of contact 2U-2l interrupts the relay energizing circuit and at the same time extinguishes the lamp L. The spring l8 now causes the armature 6 to release so that the vane I4 is caused to rotate in the clockwise direction until the pin 24 again engages the contact finger 20 and closes contact Mi-2|, whereupon the flashing cycle is repeated as long as the switch S remains closed. The rate of flashing can be controlled in a number of different ways such as by adjusting the tension of spring l8, varying the air gap of the retarding poles, altering the conductivity of the vane I4, or varying the position of the auxiliary retarding magnet l6, if one is used, to vary its retarding effect.

It will be apparent from the foregoing that I have provided a compact and reliable flashing relay of relatively simple design. Moreover, I have provided a relay which is substantially unaffected by changes in operating voltage or position in which the relay may find itself in airplane service, or by vibration encountered in such service.

Although I have herein shown and described only one form of flasher relay embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A time delay relay comprising, in combination, an operating magnetic circuit including a movable tractive armature, a winding for energizing said operating magnetic circuit, a retarding magnetic circuit having a portion common with said operating magnetic circuit and energized by said winding, and a retarding vane operated by said armature and moving in the field of said retarding magnetic circuit, whereby when said winding is energized the movement of said armature is retarded due to cutting of the retarding flux by said vane and whereby the delay time of-said relay is substantially independent of variations in the voltage applied to said winding, a change in the operating fiux causing a corresponding change in said retarding flux.

2. A time delay relay comprising, in combination, an operating magnetic circuit including a movable tractive armature, means for at times energizing said operating magnetic circuit, a retarding magnetic circuit having a portion common with said operating magnetic circuit and energized at said times by said means, an increase in the energization of said operating magnetic circuit causing a corresponding increase in the energization of said retarding magnetic circuit, and retarding means operated by said armature and comprising a conducting element moving in the field of said retarding magnetic circuit, whereby the delay time of said relay is substantially independent of variations in the degree of energization of said operating magnetic circuit.

3. A time delay relay comprising, in combination, an operating magnetic circuit including a movable tractive armature, a source of current and a winding for energizing said operating magnetic circuit, a retarding magnetic circuit having a portion common with said operating magnetic circuit and energized from said source in such manner that an increase in the voltage of said source causes a corresponding increase in the strength of both said operating magnetic circuit and said retarding magnetic circuit, and retarding means operated by said armature and comprising a conducting element moving in the field of said retarding magnetic circuit, whereby the delay time of said relay is substantially independent of variations in the voltage of said source.

4. A time delay relay comprising, in combination, two magnetic circuits in shunt with each other and having a common core portion which carries a magnetizing winding for both said magnetic circuits, a movable tractive armature operated by the flux in one of said magnetic circuits when said winding is energized, and a retarding vane operated by said armature and cutting the lines of fiux of the other of said magnetic circuits when said winding is energized to thereby oppose the movement of said armature to a greater or lesser extent according as the energization of said winding is increased or decreased respectively, whereby the delay time of said relay is substantially independent of variations in the energization of said magnetizing winding.

5. A flasher relay comprising, in combination, an operating magnetic circuit including a movable tractive armature, a retarding magnetic circuit in shunt therewith, an energizing winding for both said magnetic circuits, a retarding vane operated by said armature and moving in the field of said retarding magnetic circuit, the retarding force provided by said retarding magnetic circuit increasing with an increase in energization of said winding to thereby offset the increase in force of the operating magnetic circuit and provide a substantially uniform delay time for said relay, a control contact for said winding,

and means operated by said retarding vane for causing said contact to open or close according as said vane approaches one or the other end of its stroke respectively, said contact remaining in its last operated position to thereby provide flashing operation of said relay as long as energy is supplied thereto.-

6. A flasher relay comprising, in combination, an operating magnetic circuit including a movable tractive armature, a retarding magnetic circuit in shunt therewith, an energizing winding for both said magnetic circuits,'a retarding vane operated by said armature and moving in the field of said retarding magnetic circuit, the retarding force provided by said retarding magnetic circuit increasing with an increase in energization of said winding to thereby ofiset the increase in force of the operating magnetic circuit and provide a substantially uniform delay time for said relay, a control contact normally connected in series with said winding when the relay is deenergized, and means controlled by said armature when approaching the end of its energized stroke for tripping said contact to its open position, said contact remaining open thereafter until the armature approaches the end of its deenergized stroke whereupon the armature causes said contact to be tripped to its closed position.

' HARRY E. ASHWOR'I'H. 

